Fix for undefined methods included in ActionView

- Include Datagrid::Helper in ActionView::Base in lib/datagrid.rb
- Include Datagrid::FormBuilder in ActionView::Helpers::FormBuilder in lib/datagrid.rb
- Add action_view to spec_helper

lib/datagrid.rb

@@ -9,7 +9,11 @@ module Datagrid
   autoload :Ordering
 
   autoload :Helper
+  ActionView::Base.send(:include, Datagrid::Helper)
+
   autoload :FormBuilder
+  ActionView::Helpers::FormBuilder.send(:include, Datagrid::FormBuilder)
+
   autoload :Renderer
 
   autoload :Engine

lib/datagrid/form_builder.rb

@@ -80,5 +80,4 @@ class Error < StandardError
   end
 end
 
-ActionView::Helpers::FormBuilder.send(:include, Datagrid::FormBuilder)
 

lib/datagrid/helper.rb

@@ -36,4 +36,4 @@ def datagrid_column_classes(grid, column)
     end
   end
 end
-ActionView::Base.send(:include, Datagrid::Helper)
+

spec/spec_helper.rb

@@ -13,6 +13,7 @@
 $LOAD_PATH.unshift(File.dirname(__FILE__))
 
 require "active_record"
+require 'action_view'
 require "mongoid"
 require "mongo_mapper"
 require 'datagrid'